Jewel Basin lakes to be rid of invasive fish

By ALEX STRICKLAND - Bigfork Eagle

A project to remove all non-native and hybrid fish from a series of lakes in the South Fork of the Flathead begins this week at two lakes in the Jewel Basin Hiking Area.

Montana Fish, Wildlife and Parks' South Fork Westslope Cutthroat Trout Project will go on for 10 years in an effort to restore native Westslop Cutthroats to portions of the South Fork drainage and bolster their population in that fishery. The project includes treatment of 21 high mountain lakes in a watershed that has about 350 lakes, 50 of which support fish.

The two undergoing treatment this fall are Black Lake and Blackfoot Lake, both of which will be treated with the chemical pesticide rotenone or other fish toxicants to remove all fish in the lakes so that the Westslope Cutthroats can be reintroduced next summer. Work at Black Lake will take place from Sept. 25-27 and at Blackfoot Lake from Oct. 2-4.

All 21 lakes are on public lands with 11 in the Bob Marshall WIlderness Area, eight in the Jewel Basin and two elsewhere in the Flathead National Forest.

For safety reasons certain trails in the Jewel Basin will be closed during the treatments. Those include, from Sept. 25 -27, Black Lake; Trail 1 (from Picnic Lakes Trail 392 to Trail 55); and Trail 719 (from East Jewel Lake to Trail 1). Trails closed from Oct. 2-4 include Blackfoot Lake; Graces Creek (from Trail 719 to Road 897); Trail 1 (from Trail 719 to Road 897); Trail 719 (from bridge at North Jewel Lake to Trail 55); and Forest Road 897 above Hankerchief Lake.

FWP spokesman John Fraley said the treatments - and corresponding trail closures - are somwhat dependent on the weather, so hikers might want to call FWP to make sure the trails are open as scheduled.

"Its just a logistics issue," Fraley said. "We'll have multiple airplane flights with planes skimming in over the lake."

The chemical treatments are applied from the air with a crop duster-style plane and from shore by hand and with boats, he said.

Montana Trout Unlimited Excecutive Director Bruce Farling said TU is behind the project thanks to FWP's careful plan for application and a need for bolstering the native Cutthroat population.

"We understand and respect people's concerns about it," Farling said. "But Westslope Cutthroats are this state's heritage, it's important that we don't have hybrids."

It's the interbreeding of cutthroats and other types of trout present in the lakes that concerns FWP and Farling. Because the fish are closely enough related to reproduce, hybrid strains of fish are created that weaken the purity of the cutthroats gene pool. Besides that, Farling said, the hybrids haven't been evolving to this ecosystem for thousands of years and may not be able to handle it as well as native fish.

"We don't know that these hybrids or introduced fish are as fit in the long-term as the fish that evolved over a millenia," he said. "That genetic material evolved around fired and earthquakes and all the things nature has thrown at it over time."

One possible evolutionary advantage Farling pointed to is the effect of whirling disease on some fish populations in Montana.

"Rainbow trout around the state have really taken it on the nose," he said. "It seems Cutthroats are more resistant because of their life history. They hang out in cleaner water."

Rainbow trout originated closer to the Pacific Coast and have been introduced in every continent but Antarctica because of their allure as a sport fish.

Worth noting is that the lakes in the Jewel Basin were fishless until european arrival due to their remote location and harsh climate. The lakes have, however, been fishing spots for at least the last 80 years.

"There's a balance between a recreational fishery and conservation," Farling said. "People are used to going to these lakes and catching fish for the last 80 years. So let's make the fish compatible with the rest of the area, it's the best of both worlds."

In a comprehensive online information site, FWP documents explain the procedures involved in applying the fish toxicants and the risks associated with the chemicals.

Rotenone and antimycin, the other chemical commonly used in fish control, work by stopping the oxygen transfer in fish's vital organs. Only small concentrations are required, so FWP uses a motorboat and pump to mix the chemicals effectively and quickly. The chemicals also detoxify quickly enough so as to be no threat to groundwater, according to FWP documents. Both are neutralized by organic substances and studies have shown that rotenone only travels one inch through soil before being neautralized.

After the treatment is completed, Fraley said FWP will string out gill nets to check for any significant amount of remaining fish.

"There is no way to say that every fish is dead," he said. "Though we're hoping."

Restokcing will happen early next summer and Fraley said catchable-size fish will be among those put in the lakes. The lakes will also be open to anglers as usual next summer.

Updates on the project will be posted within days of treatment on FWP's Westslope Cutthroat Trut Project Web site at http://fwp.mt.gov/r1/wctproject/default.html.